Inductionin Vitroof Mucification of Rat Cumulus Oophorus by Gonadotrophins and Adenosine 3′,5′-Monophosphate*

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Abstract
The ability of LH [luteinizing hormone] in vitro to induce the intercellular mucification which occurs in vivo just before ovulation, was observed. The test was to measure the ability of bovine testicular hyaluronidase (1 mg/ml) to lyse the cumulus mass. Isolated cumulus-oocyte complexes were cultured for 24 h in the presence of LH, FSH [follicle stimulating hormone], hCG [human chorionic gonadotropin], 1 of 4 c[cyclic]AMP derivatives, or 3 phosphodiesterase inhibitors. All were shown to be capable of inducing mucification. Timing of the mucification response to FSH and LH was made by examining cultures at hourly intervals. In the presence of 10 .mu.g/ml NIH[National Institute of Health]-LH-B9, mucification appeared after a latent period of 4 h; maximal occurrence of mucification was at 16 h, and half-maximal was at 6.25 h. In cultures incubated with NIH-FSH-S11, these times were 6.0, 19.0, and 9.25 h, respectively. Times for 0%, 50%, and 100% response were 4.0, 6.25, and 16.0 h for LH and 6.0, 9.25, and 19.0 for FSH. From analysis of the dose-response relationship for LH, the ED50 was found to be 2.8 .mu.g/ml. The dose used routinely, 10 .mu.g/ml, was 88% effective. Exposure of cumulus-oocyte complexes to LH for 15, but not 5, min sufficed for the induction of the mucification response. Cumulus cells respond directly to gonadotrophic stimulus. Their response is presumably mediated by cAMP.

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